Hollow pole



H. K. WALKER HOLLOW POLE Aug. 9, 1927.

Filed April 27. 1925 Patented Aug. 9, 1927.

UNITED STATES v 1,638,515 PATENT OFFICE.

HENRY KERSHAW VJALKER, OF LONDON, ENGLAND.

HOLLOI/V I POLE.

Application filed April 27, 1925, Serial No. 25,990, and in Australia June 11, 1924.

This invention relates to the construction of hollow or tubular poles, masts, conduits and the like from metal or other suitable material andrefers more particularly to a construction in which such articles are formed by spirally or helically coiling a strip ofsuitable material upon itself the ends of the helically coiled stripabeing secured so as to form a hollow tube of light 10 and strong construction, which taper from end to end.

The object of the presen invention is to provide'an improved article of the above nature and a method of making the same 10 whereby the helical convolutions of the pole or the like are effectively secured against longitudinal or downward collapse without the aid of rivets or other fastening means, except where the ends of the coiled strip 2&1 are secured or fastened to prevent unwinding thereof.

The chief characteristic of the invention resides in the provision of an outstanding rib or projection on the metal or other strip so that, when the latter is coiled into its helical form, this outstanding rib or projection on each convolution rests on the up per edges of the convolutionimmediately beneath or adjoining, thereby effectively 5L preventing the slightest collapse or longitudinal displacement of the tube" coils. At the same time this outstanding rib or projection which extends throughout the length of the helically coiled strip, serves greatly to increase the strength and rigidity of the pole or the like and also prevents water entering between the convolutions.

In constructing a pole, mast or like tubular article in accordance with the invenv tion a strip of metal or other suitable material of the desired width has formed thereon an outstanding rib or projection extending lengthwise of the strip and preferably throughout its length. This rib or projection may be formed by any suitable means such for instance as by heating the metal.

strip and pressing out a solid longitudinal rib thereon by the aid of rollers or by any other suitable means for the purpose. The

rib or projection may, however, be expressed from or embossed on the metal strip.

Obviously various other methods may be adopted in the formation of the longitudinal rib but it is preferable that the latter should be of substantially square or rectangular shape in cross section so that its edge will verse width of the outstanding rib should be approximately equal to the thickness of the strip so that the rib will neatly overlap the edge of the coiled strip.

The said longitudinal rib or projection extends parallel to the edges of the strip and is preferably formed closer to one edge thereof thanthe other, the narrower or upper part of the strip which extends'between the said edge and theoutstanding rib being exposed in the finished tubular article whilst the other or wider part of the strip beneath the rib is encased in the surrounding convolutions of the pole or the like.

In forming the tubular articles a strip provided with an outstanding longitudinal rib as above mentioned may be coiled around a tapered mandrel in such a manner that the upper edge of the successive convolutions lies closely against. the adjacent or lower edge of the'outstanding rib which thus extends helically around theexterior of the tube fromend to end thereof and serves effectively to prevent downward or longitudinal collapse of the superposed convolutions. When the coiling operation has been completed the extremities of the strip are secured to the adjacent convolutions by welding, soldering, clamping or other suitable means withthe result that an extremely strong, rigid and eflicient article is provided in a simple and inexpensive manner.

Poles, masts or like tubular articles manufactured as above described may be galvanized, sherardized, painted or otherwise treated or the strip from which the article is made may be similarly treated prior to the coiling of the strip around the mandrel.

In the accompanying drawings illustra tive of the invention, Fig. 1 is a fragmentary View of one form of the strip used prior to coiling while Fig. 2 is a fragmentary view of a strip after coiling; Fig. 3 is a vertical section of the upper portion of Fig. 2. Fig.

i is a fragmentary view of a modified form of strip.

As shown, the strip a from which the tube, pole or the like is made is formed with a longitudinal rib 6 extending preferably closer to one edge of the strip than to the other The rib as shown is, of substantially square or rectangular shape in cross section so that its edge will closely and neatly rest against the edge of the adjoining convolution of the strip when the latter is coiled into its helical form. Preferably also and as shown the thickness or transverse width of the outstanding rib is approximately equal to the thickness of the strip so that the rib will neatly overlap the edge of the coiled strip.

The rib extends parallel to the edge 0 of the strip and, as shown, is preferably, formed closer to one edge thereof than the other, the narrower or upper part of the strip which extends between the said edge and the outstanding rib exposed in the finished tubular article whilst the other or wider part of the strip beneath the rib is encased in the surrounding convolutions of the pole or the like. The strip so formed is coiled around tapered mandrel or the like in such manner that the edge 0 of the successive convolutions lies close against the lower edge of the outstanding rib b which thus extends helicaily around the exterior of the tube thereby formed and serves effectively to prevent longitudinal collapse of the superposed convolutions. The rib or projection b is conveniently formed by heating the metal strip and pressing out a solid longitudinal rib thereon by the aid of rollers in wh ch case the rib will take the form shown in Figs. 1 to 3. The rib 2 may, however, be formed by embossing the metal of the strip and will then take a form such as the. v shown in Fig. &.

Various adjuncts or accessories may be employed, for instance, to close the opening at the top or smaller end of the tapered tube and to provide for the attachment of outstanding arms or the like, as for example, when the tubular pole is to be employed as a support for telegraph or telephone wires or for other similar purposes. Furthermore may be coiled around su 2h end portion, or a protective sheath of cement, metal or other material may be cast upon or secured to it.

Various other alterations, modifications and/or additions may be incorporated in the construction of the improved article without departing from the spirit and scope of the invention.

I claim: 7

1. A tubular article comprising a helically coiled. strip of material formed on one side only with a longitudinally extendingrib, said rib projecting from the surface of said strip a distance equal to the thickness of said strip so as to present when coiled an outer surface flush with the adjacent convolution.

A tapered tubular pole comprising a metal strip having on one'side a longitudi nally extending rib, said rib being substantially rectangular in cross section and of a transverse thickness equal to the thickness of the strip, said stri being coiled to form a plurality of contacting helical eonvolutions, the rib on each convolution being supported b the convolution immediately preceding forming with it a flush surface, substantially as and for the purpose set forth.

3. A metal strip adapted to be coiled helically to form poles and the like, comprising a fiat face, and on said flat face, nearer the one end than the other, a rib of substantially rectangular cross-section, projecting from said face a distance equal to the thickness of paid strip, substantial y as and for the purpose setforth.

In testimony whereof I have signed my name to this specification.

HENRY KERSHATV WALKER. 

